Chapter 6: Operation
LAN Performance Verification Level 1 displays the projected speed capability of the cable. The graph is a result of thousands of measurements used to project the speed of the cable. This is one of the most useful and
Figure 6-24. Length/Timing summary screen.
Length: The length of the shortest cable pair (in feet). 330 feet (100 m) is the longest cable allowed by the 802.3 standard. The LAN Performance Verifier can test cables up to 1250 feet (381 m) in length.
Propagation delay: The time it takes for a data signal to travel the length of the cable (in nanoseconds). An abnormally long propagation delay indicates the cable is “too slow” for the application. Either the cable itself is too slow or there is an error in the wiring. The standard allows a maximum 555 nsecs propagation delay (CAT6 cables).
Skew: The difference in the propagation delay between the slowest pair and the fastest pair in the cable (in nanoseconds). A small skew ensures that data, on each pair, will arrive at the receiver at about the same time. A large skew reading causes errors. 50 nsecs is the maximum allowable skew.
To continue reviewing, press the down arrow key q.
Page 34